Insulator



Patented May 15, 1928.

STATES rate FREDERICK H. MILLER, 01? WILKINSBUBG, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COIMIPAN"5Z, A CORPORATION OF PENNSYL- VANIA.

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Application filed. September 19, 1922. Serial No. 589,088.

My invention relates to insulators and particularly to high-potential insulators of the suspension type.

One object of my invention is to provide a device of the above-indicated character that shall have greatly improved insulating characteristics.

Another object of my invention is to provide a suspension insulator of such construction as to permit its use in connection with voltages considerably above that for which similar insulators, now employed and of the same size and weight, are adapted.

A further object of my invention is to provide a novel means for sealing the normally open end of a suspension insulator of bell-shape and for preventing lateral relative movement between the tension member and the insulator at said end.

Heretofore, in insulators of the pin type for mounting in rigid vertical position on cross arms, it has been usual to employ wood pins. Such pins, however, were subject to deterioration by moisture and sometimes became so charred as a result ofcorona formation in high potential service as to practically destroy the voltage resistance of the insulator. lhis feature resulted in breakdown, renewal of parts and other trouble and expense. Consequently, it has, since the original Wide use of wood pins in the rigid cross-arm type of insulator above referred to, been customary to employ metal pins. The above fact, that the evolution or progress in the art of constructing rigidlymounted cross-arm insulator pins has been from wood to metal or, in other words, from insulating material to conducting material, is to be especially noted because, by my invention, I so construct an insulator embodying an insulating pin as to overcome the'objections referred to and obtain advantages that are not possible with a metal pin.

As the voltages of commercial power circuits increased in value, another important step in the evolution of supporting the conductoroccurred when, as the apparent limit to the size and strengthof the rigid pintype insulator was reached, the high-potential suspension insulator came into general use. By the use of the latter, much greater insulating distances, were readily obtained, so that great increases in the value of the power circuit voltages were permissible. However, here again, limits have been reached beyond which it is desired to go.

The adoption of the present standard types of suspension insulators for high-potential service introduced new factors, not the least of which is that the load forces on the member corresponding to the pin of the rigid type insulator are opposite in direction to'those in the pin. Thus, the member corresponding to the pin supports the entire load forces in tension. Accordingly, the construction and material of the tension member and its manner of attachment to the insulator are selected for different considerations than are the same features in an insulator of the rigid type. To the best of my knowledge, no material other than metal has ever been employed in the tension members to alone sustain the load in suspension insulators of the type to which my invention appertains and, aside from thermal expansion troubles, metal has been admirably adapted for the insulators in which it has been employed.

One of the latest developments in the suspension insulator art is a demand for a longer unit and the early suggestions have merely increased the length of the metal tension members.

It is my aim to further increase the voltages by which commercial electric power may be transmitted, by eliminating some of the metal as heretofore employed. In practicing my invention, I provide a suspension insulator unit, particularly adapted as one of the above-mentioned longer units, in which the tension member is constructed of insulating material and is so protected as to be free of the objections of charring and deterioration by moisture. Further, the construction is such as to provide sufiicient mechanical strength and, by more widely separating the metal terminals, materially improves the insulating property of the insulator.

The single figure of the accompanying drawing is a side view, in longitudinal section, of a suspension insulator embodying my invention.

The device comprises, in general, a main insulating body member 2, preferably of porcelain, a tension member 3, metal ter- I minal members 4 and 5, an anchor member or surface-creepage portions 9 and an end skirt 10. The terminal member 4, having an eye or clevis 11 thereon, is of substantially cup-shape closely conforming to the end portion 8 of the insulating member 2 and is preferably cemented to the portion 8,'in accordance with established practice.

The tension member 3 is constructed of fibrous insulating material, such as wood,

and maybe similar to an ordinary low-voltage wood-strain insulator having frusto-conical ends 1d and 15.

Theanchor member 6, corresponding to the pin of a suspension insulator of a usual type and, also,in, this instance, to the terminal member of an ordinary wood-strain insulator, is constructed of a body of malleable metal ofcup shape swa-ged in position over the frusto-conical portion 14: of the tension member 3, and is-provided with sloplng outer surfaces to resolve longitudinal tension load forces into lateral compression forces againstthe portion 8 of the insulating member 2. A body of cement 16 secures the anchor member 6 in position.

The terminal member 5, corresponding to the outer end of the metal pin of 'a suspension insulator of a usual type and, also, in this instance, to the other terminal of an ordinary Wood-strain insulator, is also constructed of a body of malleable metal of cup-' shape swaged in position over the frustoconical portion 15. The member 5 is further provided with a screw-threaded portion l7 having rounded threads.

The sealing member 7 is preferably constructed of resilient sheet metal in the form of a sleeve or cylinder having a pressedthreaded portion 17 for co-operation with the terminal member 5. A flange 19, at the outer end of the member 7 is provided for screwing the latter in position.- The member 7 further comprises a lateral flange 20, at its inner end, which may be provided with annular corrugations, and is of such shape.

and diameter as to snap over an annular rib or flange 21, on the inner surface of the skirt 10, when it is advanced inwardly along I the portion 17. A body of cement 22 may be provided between the outer edge of the flange 20 and the inner surface of the skirt 10, above the rib 21 and, similarly a suitable sealing medium, such as White lead, may be provided between the threads of the portions17 and 18 to effectively seal the inner portions of the insulator.

Further, by reason of the construction ofthe flange 20, the member 7 permits relative movement between the members 2 and 3 without breaking the seal. Relative movement may be caused by temperature changes or by slight stretching of the member 3 under tension.

Since the insulator is entirely free of metal and other conducting parts, between the metal members 5 and 6, and since no moisture can gain access to the interior of the body member 2, a suspension insulator is obtained which is much more eifective than similar insulators heretofore suggested.

The interior space between the members 2- portion of substantially cup-shape, a pin including a fibrous insulating portion and one end cemented in position insaid head portion, and means on the pin for effecting bet ter holding cooperation between the fibrous material of the pin and the cement including amoisture-impervious covering on said end.

2. A high-potential suspension insulator of the cap-and-pintype comprising a refractory dielectric body member having'a head portion of substantially,cup-shape, a pin including a fibrous insulating portion and one end cemented in position in said head portion, and meansfor effectingbetter holding cooperation between the fibrous material of the. pin and the cement including a metal head member on said end 3. A high-potential suspension insulator of the cap-and-pin type comprising a refractory dielectric body member having a head portion of substantially cup-shape, a pin including a fibrous insulating portion and one end of substantially inverted frusto-coni'cal shape cemented in position in said head portion, and means for effecting better holding cooperation between the-fibrous material of the pin and the cement including a metal cap swgged in position over said frusto-conical en 4. A high-potential suspension insulator of the cap-and-pin type comprising a refractory dielectric portion of substantially cupshape, a tension pin including a fibrous insulating portion and one end secured in position in said cup portion, and means for totally enclosing the pin including ametal terminal member at each end of the pin and a tubular refractory portion surrounding the."

of the cap-and-pin type comprising a refractory dielectric body member having a head portion of substantially cup-shape, a pin including a fibrous insulating portion and one end bonded in position in said head portion and means-for efiecting better holding co-operation between the fibrous material of the pin and the bonding medium including a metal head member on said end.

6. A high-potential suspension insulator of the cap-and-pin type comprising a refine-- tory dielectric body member having a head portion of substantially cup-shape, a pin including a fibrous insulating portion and one end bonded in 'position in said head portion, and means on the pin including a covering on said end having better cooperation with the bonding material and with the fibrous i material than exists between the fibrous material of the pin and the bonding material.

7. A high-potential suspension insulator of the cap-and-pin type comprising'a refractory dielectric body member having a head portion of substantially cup-shape, a pin including an insulating portion and one end bonded in position in said head portion, and means for efiecting better holding co-operation between the insulating material of the pin and the bonding material including a metal covering on said end.

In testimony whereof, I have hereunto subscribed my name this 13th day of September,

FREDERICK H. MILLER. 

